5.2 Vaccine-Preventable Diseases and Immunization Schedules

Measles (Rubeola), Mumps, and Rubella (German Measles)

Vaccine-preventable viral exanthems require prompt recognition, immediate isolation, and rapid public health notification by the school nurse. High herd immunity rates are necessary to prevent classroom outbreaks.

Measles (Rubeola)

Measles is an extremely contagious paramyxovirus transmitted via airborne respiratory droplets that can remain suspended in air for up to 2 hours after an infected person leaves a room. The incubation period is typically 10 to 12 days to prodrome and 14 days to rash onset.

• Clinical Presentation:
  • Prodrome: High fever (often >103°F [39.4°C]) accompanied by the classic "3 Cs": Cough, Coryza (rhinitis), and Conjunctivitis.
  • Pathognomonic Sign: Koplik spots—small, irregular red spots with bluish-white centers on the buccal mucosa opposite the lower molars, appearing 1 to 2 days before the generalized rash.
  • Exanthem: Erythematous maculopapular rash that begins at the hairline/face and spreads cephalocaudally (downward to the trunk and extremities), becoming confluent.
• Exclusion & Post-Exposure Protocol:
  • Exclude confirmed cases until at least 4 full days after the appearance of the rash.
  • Unimmunized contacts must be excluded from school for 21 days after their last exposure or until fully vaccinated. MMR vaccine administered within 72 hours of exposure or Immune Globulin (IG) within 6 days may provide post-exposure prophylaxis (PEP).

Mumps

Mumps is a paramyxovirus transmitted through direct contact with saliva or respiratory droplets. Incubation ranges from 12 to 25 days.

• Clinical Presentation: Painful swelling of the salivary glands, most commonly parotitis (unilateral or bilateral parotid gland swelling). Systemic features include low-grade fever, headache, myalgia, and anorexia. Complications include orchitis (testicular inflammation in post-pubertal males), oophoritis, aseptic meningitis, and sensorineural hearing loss.
• Exclusion Criteria: Exclude student for 5 days after the onset of parotid swelling.

Rubella (German Measles)

Rubella is a togavirus causing a mild viral exanthem in children but posing severe teratogenic risks (Congenital Rubella Syndrome [CRS]—cataracts, cardiac defects, sensorineural deafness) to pregnant staff or family members exposed during early gestation.

• Clinical Presentation: Low-grade fever, maculopapular rash starting on the face and spreading downward (fading in 3 days), accompanied by tender postauricular and suboccipital lymphadenopathy.
• Exclusion Criteria: Exclude student for 7 days after rash onset.

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Varicella-Zoster Virus (Chickenpox)

Varicella is an airborne and direct-contact pathogen caused by the varicella-zoster virus (VZV). The incubation period ranges from 10 to 21 days (mean 14–16 days). Individuals are contagious from 1 to 2 days before rash onset until all lesions are fully crusted.

Clinical Presentation

• Classic Exanthem: Pruritic rash presenting in successive crops over 3 to 5 days. Lesions evolve rapidly from red macules to papules, to clear vesicles on an erythematous base (described as "dewdrops on a rose petal"), which subsequently umbilicate and crust over. A hallmark feature is the simultaneous presence of lesions in all stages of development.
• Breakthrough Varicella: Mild varicella disease occurring in a previously vaccinated individual (>42 days post-vaccination). Breakthrough cases typically present with fewer than 50 lesions, predominantly maculopapular rather than vesicular, with lower fever and shorter duration. However, breakthrough cases remain contagious.

School Exclusion Guidelines

Students with varicella must be excluded from school until all vesicles have completely dried and crusted over (typically 4 to 7 days after rash onset). In breakthrough varicella without vesicles, exclude until no new lesions appear within a 24-hour period.

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Pertussis (Whooping Cough)

Pertussis is a highly contagious bacterial respiratory infection caused by Bordetella pertussis, transmitted via respiratory droplets. It is particularly dangerous in infants and unimmunized children.

Clinical Stages of Pertussis

1. Catarrhal Stage (1–2 weeks): Insidious onset of mild upper respiratory symptoms (coryza, low-grade fever, mild cough). Highest contagiousness occurs during this stage, often mistaken for a common cold.
2. Paroxysmal Stage (2–6+ weeks): Characterized by severe fits of rapid, staccato coughing (paroxysms) during a single expiration, followed by a high-pitched inspiratory "whoop" as air is drawn back through a constricted glottis. Accompanied by post-tussive emesis and facial cyanosis.
3. Convalescent Stage (Weeks to Months): Gradual recovery; coughing fits decrease in frequency and severity over 2 to 3 weeks.

Vaccine Formulations & Age Rules

• DTaP (Diphtheria, Tetanus, acellular Pertussis): Formulated with higher antigen concentrations (denoted by capital letters) for infants and young children under 7 years of age (standard 5-dose primary series at 2, 4, 6, 15-18 months, and 4-6 years).
• Tdap (Tetanus, reduced Diphtheria, acellular Pertussis): Formulated with reduced diphtheria and pertussis toxoids (denoted by lowercase letters) for individuals 7 years of age and older (standard adolescent booster dose at 11–12 years).
• Exclusion & PEP: Exclude suspected/confirmed cases until completion of 5 full days of appropriate oral antibiotic therapy (e.g., azithromycin, clarithromycin). Without antibiotics, exclude for 21 days from cough onset. Post-exposure antibiotic prophylaxis is recommended for all household and close classroom contacts regardless of immunization status.

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Human Papillomavirus (HPV) & Meningococcal Disease

Human Papillomavirus (HPV)

HPV is the most common sexually transmitted infection in the U.S., causing cervical, anal, oropharyngeal cancers and genital warts (types 6, 11, 16, 18). The 9-valent HPV vaccine (Gardasil 9) is recommended by ACIP for all preteens at 11 to 12 years (can start at age 9):

• 2-Dose Series: If the first dose is administered before the 15th birthday (doses given 6–12 months apart).
• 3-Dose Series: If the series is initiated on or after the 15th birthday (schedule: 0, 1–2, and 6 months).

Invasive Meningococcal Disease

Caused by Neisseria meningitidis (serogroups A, C, W, Y, and B), meningococcal disease presents abruptly with high fever, severe headache, nuchal rigidity, photophobia, altered mental status, and a characteristic petechial or purpuric skin rash. It can progress rapidly to septic shock, limb amputation, or death within hours.

• MenACWY (Quadrivalent Conjugate): Routine ACIP recommendation: Dose 1 at age 11–12 years, followed by a booster dose at age 16.
• MenB (Serogroup B Vaccine): Recommended for high-risk groups (e.g., complement deficiency, asplenia) and approved for healthy adolescents aged 16–23 years under shared clinical decision-making (preferred timing 16–18 years).
• Post-Exposure Prophylaxis: Close contacts (household members, daycare contacts, or anyone exposed to oral secretions) require immediate PEP with Rifampin, Ciprofloxacin, or Ceftriaxone.

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ACIP Immunization Schedules & Herd Immunity

Herd immunity (community immunity) occurs when a sufficient percentage of a population is immune to an infectious disease (through vaccination or prior illness), making spread from person to person unlikely. Thresholds vary by infectivity ($R_0$):

• Measles ($R_0 = 12 ext{–}18$): Requires 95% population immunity.
• Pertussis ($R_0 = 12 ext{–}17$): Requires 92% to 94% population immunity.
• Rubella ($R_0 = 6 ext{–}7$): Requires 83% to 85% population immunity.